Arachidonic acid levels will be determined during the evolution of a standardized inflammatory stimuls (patch test reaction). These levels will be correlated with alterations of levels of eicosatrienoic acid (20:3, n-9) and of lysolecithin, two lipids present in skin known to inhibit prostaglandin biosynthesis. Further characterization of an intranuclear factor in skin that interferes with two standard assays of lymphocyte function, mitogen-induced transformation and cytoxicity, will be undertaken.